Changes of extremity and laryngeal muscle electromyographic amplitudes after intravenous administration of vecuronium.
OBJECTIVE
To compare electromyographic (EMG) amplitude changes in extremity and laryngeal muscles after vecuronium administration and study the effects of topical lidocaine on laryngeal EMG in a swine model.


METHODS
Prospective animal study.


METHODS
Electrically evoked EMG activities were recorded from the vocalis muscles (directly and via an EMG endotracheal tube) and from the flexor digitorum muscles before and after intravenous vecuronium administration. EMG amplitudes were followed for 30 minutes after vecuronium injection together with monitoring of limb twitches to train-of-four stimulation. The testing was repeated after a 30-minute wash-out period and with topical lidocaine.


RESULTS
EMG amplitude recovery occurred sooner and more quickly in flexor digitorum muscle than in vocalis muscles. Reappearance of four twitches corresponded to EMG amplitude recovery to about 80% of the baseline in flexor digitorum muscles and to about half-baseline size in vocalis muscles. EMG amplitudes were generally lower at the start of the second round testing than the first round, with somewhat slower recovery in vocalis muscles.


CONCLUSIONS
In contrast to reports by others in human studies, extremity muscles seem to be more resistant to vecuronium at 0.1 mg/kg than laryngeal muscles in the swine. Reappearance of four twitches corresponds to 50% of laryngeal EMG recovery and indicates adequate condition for monitoring electrically evoked laryngeal EMG activities. This study is inconclusive regarding the effects of topically applied lidocaine on laryngeal EMG amplitudes. Translation of these data to humans should be done with caution.
Shi
Yongbing
Y
Department of Otolaryngology, Head and Neck Surgery, Oregon Health and Science University, Portland, OR, USA. shib@ohsu.edu
Hou
Vivian
V
Tucker
Anne
A
Cohen
James
J
D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D004576:Electromyography / Q000187:drug effects*; D007262:Infusions, Intravenous; D007821:Laryngeal Muscles / Q000187:drug effects*; D008012:Lidocaine / Q000494:pharmacology; D016343:Monitoring, Intraoperative; D018482:Muscle, Skeletal / Q000187:drug effects*; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology*; D061226:Recurrent Laryngeal Nerve Injuries; D013552:Swine; D014673:Vecuronium Bromide / Q000494:pharmacology*; D014826:Vocal Cord Paralysis / Q000209:etiology / Q000517:prevention & control
D000779:Anesthetics, Local; D009467:Neuromuscular Depolarizing Agents; D014673:Vecuronium Bromide; D008012:Lidocaine